It is desirable to carry out combustion with as high efficiency as possible as this makes the combustion operation more economical while simultaneously reducing the amount of pollutants generated by the combustion process. When the fuel employed in the combustion process has relatively uniform properties and high heating value, efficient combustion may be relatively easily attained by matching the oxygen available for combustion to the stoichiometric oxygen requirement of that fuel. However, when the fuel has a relatively low heat content or a non-uniform and highly variable stoichiometric oxygen requirement it is much more difficult to carry out combustion at high efficiency.
Accordingly, it is an object of the invention to provide a process for combusting fuel and oxidant at high efficiency.
It is a further object of this invention to provide a process for combusting fuel and oxidant at high efficiency even when the fuel has a non-uniform and/or highly variable stoichiometric oxygen requirement.
It is known that the efficiency of a combustion process may be enhanced by the use of pure oxygen or oxygen-enriched air as the oxidant in place of air. Because pure oxygen or oxygen-enriched air contains much less inerts than does air for an equivalent amount of oxygen available for combustion, much less energy is expended pressurizing, pumping and heating these inerts when pure oxygen or oxygen-enriched air is employed as the oxidant. The elimination of this non-productive handling and heating of inerts significantly enhances the efficiency of the combustion process.
The use of pure oxygen or oxygen-enriched air is well known to cause the combustion reaction temperature to increase. The increased temperature favors the kinetics of the combustion reaction toward the formation of nitrogen oxides (NO.sub.x). This is undesirable because NO.sub.x is a significant environmental pollutant.
Accordingly, it is another object of this invention to provide a process for combusting fuel and oxidant, particularly pure oxygen or oxygen-enriched air, at high efficiency while also experiencing low NO.sub.x generation.
It is yet another object of this invention to provide a process for combusting fuel and oxidant at high efficiency and with low NO.sub.x generation even when the oxidant is pure oxygen or oxygen-enriched air and when the fuel has a non-uniform and/or highly variable stoichiometric oxygen requirement.